Making Links 2 – Practical work

In Making Links 1, we considered how encouraging students to make links and explore examples of biological concepts in plants as well as animals can help them to gain a greater understanding of universal biological processes. We also asked you to reflect upon some of the teaching and learning strategies that can help you and your students to make links between the topic of stem cells and other areas of the biology curriculum. Making Links 2 will highlight the role that accessible plant-based investigations can play in helping to overcome potential barriers to teaching and learning about stem cells.

In this article, using content from an online course developed by SAPS and STEM Learning, we will look at three practical activities that will support your students’ understanding of plant stem cells and enable them to make connections to other areas of the curriculum.

Taking cuttings

Taking a cutting is the easiest way to produce a clone of a plant – that is, each plant is genetically identical to the parent plant. Plants are very easy to clone because, unlike animal cells, many plant cells are totipotent, meaning that each cell has the capacity to regenerate the entire plant. This fact lies at the foundation of all tissue culture work.

Next, we’ll look at an investigation into plant tissue culture that your pupils can carry out.

Cauliflower cloning

This practical provides first-hand experience of plant tissue culture, a technique that is widely used in conservation biology, in horticulture for the inexpensive propagation of many clones of a particular plant and in gene technology for the cultivation of genetically modified cells into complete plants. This can also be used to bring ethical, legal, and social dimensions into this section of the curriculum.

Micropropagation is the regeneration of whole plants from small pieces of plant material. These small pieces (known as ‘explants’) are grown on sterile media and the plants produced can be potted up in soil and transferred to the glasshouse/field. Various parts of a plant can be cultured; plants have been regenerated from leaves, stems, roots, meristems, flowers and even pollen or ovules. In this case, students use a tiny piece of a cauliflower. Since all the explants come from the same cauliflower, the new plants will be clones of each other.

You can find student, teaching and technical guides for the cauliflower cloning practical on the resource page.

We will now look at our final practical, which allows students to see the stages of mitosis as cells divide.

Root tip mitosis

Usually, when you look at a cell under a microscope, the nucleus just looks like a dark spot and you cannot see the individual chromosomes within it. However, when a cell divides, the chromosomes become visible. When this happens it is possible for students to see how the chromosomes move as the cell passes through each stage of cell division.

Meristems are structures at the ends of roots and shoots where plant stem cells divide by mitosis (cell division) to form identical daughter cells. In this practical, students prepare and observe cells in various stages of mitosis from the meristems of garlic root tips that were actively growing moments before the practical commenced.

You can find full student, teacher and technical guides to this practical investigation on the resource page.

Why don’t we grow back body parts?

Let’s re-visit our 15 year old’s amazing question posed in Making Links 1:

An answer to this question will draw upon your understanding of cell division, stem cell biology, cell differentiation and the persistence of totipotency in plant stem cells but not in animal stem cells.

However, as we all know, one amazing question often inspires another, so how will you respond to the student who asks:

Watch this video for some thought-provoking ideas to help you to answer this question.

Conclusion

Plant-based practical investigations provide valuable first-hand opportunities for students to think scientifically about topics such as stem cells, in the setting of a school laboratory. Many of the processes that are seen in animals also take place in plants. The inclusion of plants in practical investigations and biology schemes of work can really help students to make links across the biology curriculum and gain a greater understanding of universal biological processes, using living organisms that are familiar and readily accessible to them every day.

This article was written using reworked content from the course Teaching Biology: Inspiring Students with Plant Science codeveloped by SAPS and STEM Learning.